To resolve the problem about the redundant in thrust allocation,an cost function was proposed in this paper.In the function,not only the net force error between the desired force vector and net force generated by thrusters into account was taken,but also the consumption of jet.And then,according to symmetry principle of the force vector generated by the thrusters,the search range is reduced from 256 to 11,and the computation is largely reduced;Finally,mathematical simulation results show that the approach is reasonable and effective,and it provides theoretical basis for hardware-in-loop simulation.